GraphPi is being refactored. The official version will be released in the final version of our paper.
In this section, you will learn how to run GraphPi on a single machine with multi-threads (using OpenMP).
The class DataLoader is used to load the dataset(i.e., data graph). And the dataset is stored in class Graph .
The format of the dataset may be a little different from its download version. The first line should contain two integers: the number of vertices and the number of edges respectively. From the second line, each line contains two integers xand y, representing an undirected edge (x,y) in the graph. The wiki-vote dataset has been placed at GraphPi/dataset/wiki-vote_input as an example.
Since GraphPi's performance model needs the number of triangles of the dataset, if you want to use a new dataset, you need to add a new DataType and a corresponding constant variable named dataset_tri_cnt representing the number of triangles in include/dataloader.h (see our code for more detail). And we have already prepared these classical datasets for GraphPi in include/dataloader.h: Patents ,Orkut ,LiveJournal, MiCo, Twitter, CiteSeer and WikiVote.
When the dataset is prepared, we can load the dataset easily. First, you need to define a pointer of a graph and a dataloader.
Graph *g;-
Dataloader D;Then, you need to use std::string to assign the dataset's name and file path.
const std::string type_str = "Wiki-Vote";
const std::string path = "./datasets/wiki-vote_input"In include/common.h, we provide many functions to make your coding more easy. Using GetDataType to transform std::string to DataType.
DataType my_type;
GetDataType(my_type, type_str);Now you can load the dataset using the function load_data(). If it failed to load the dataset, this function returns false.
assert(D.load_data(g,my_type,path.c_str()));After steps above, you have a graph g which contains the dataset.
The class Pattern is used to store a pattern. Taking Rectangle as an example, three ways are enabled to define the pattern.
The first one is adding each edge of a pattern one by one.
int size = 4;
Pattern p(size);
p.add_edge(0,1);
p.add_edge(1,2);
p.add_edge(2,3);
p.add_edge(3,0);
// Rectangle is like :
// 0 -- 1
// | |
// 3 -- 2
Since the Rectangle pattern is used frequently, we provide an easier way for you to load this pattern.
Pattern p(PatternType::Rectangle);
The third way is providing an adjacency matrix in an array.
int size = 4;
char adj_mat[17] = "0101101001011010"; // the vertex 0 has neighbor 1 and 3, so the first four character "0101" means 0 have edges to 1 and 3 but not have an edge to 0 or 2.
Pattern p(size, adj_mat);Three things you need to decide in this step : 1) performance modeling type 2) restrictions type 3) use inclusion-exclusion optimization or not.
In class Schedule, you can see the constructor function :
Schedule(const Pattern& pattern, bool& is_pattern_valid, int performance_modeling_type, int restricts_type, bool use_in_exclusion_optimize, int v_cnt, unsigned int e_cnt, long long tri_cnt);For performance_modeling_type, 0 means not to use any performance modeling; 1 means to use GraphPi's performance modeling.
For restricts_type, 0 means to use not restrictions; 1 means using GraphPi's restriction generator.
v_cnt, e_cnt and tri_cnt mean the numbers of vertices, edges and triangles of the dataset respectively.
And you need to use variable pattern defined in the step 1.
So, if we want to use GraphPi's performance model and restrictions with inclusion-exclusion optimization, you should run like this :
int performance_modeling_type = 1;
int restricts_type = 1;
bool use_in_exclusion_optimize = true;
bool is_pattern_valid;
Schedule schedule(pattern, is_pattern_valid, performance_modeling_type, restricts_type, use_in_exclusion_optimize, g->v_cnt, g->e_cnt, g->tri_cnt);
assert(is_pattern_valid);GraphPi is based on OpenMP to enable multi-threads, so you need to decide how many threads to use in the process of pattern matching. In our experiment, we use 24 threads since each node has 2 12-core processors.
int thread_num = 24;
Now, we can run the member function pattern_matching of the class Graph.
long long ans = g->pattern_matching(schedule, thread_num);
The result (i.e., the number of embeddings) is stored in ans.
If you are still confused, you can see tianhe/baseline_test.cpp as an example. This program is following steps above.
GraphPi uses MPI to implement the distributed version.
You can see src/run_mpi_trivial.cpp as an example.
The parameters used in the distributed version are the same as those used in the single node version. You can choose to pass parameters through the command line or modify them directly in src/run_mpi_trivial.cpp.
Note that if you run more than 24 threads on a node, you need to modify the MAXTHREAD variable in the include/graphmpi.h.
Some codes should be modified to enable your own dataset. Please follow the steps below.
GraphPi only accepts input dataset of specific format:
The first line should contain two integers: the number of vertices and the number of edges respectively. From the second line, each line contains two integers `x`and ` y`, representing an undirected edge `(x,y)` in the graph. The wiki-vote dataset has been placed at GraphPi/dataset/wiki-vote_input as an example.
And the dataset needs a name, taking MyDataset as an example.
The name MyDataset should be added to DataType:
enum DataType {
Patents,
Orkut,
...
MyDataset,
Invalid
}And because GraphPi's performance model needs the number of triangles in the dataset, a constant should be added (Assuming that there are 10000 triangles in MyDataset) :
const long long MyDataset_tri_cnt = 10000LL;
The function load_data and general_load_datashould be changed.
In functionload_data, MyDataset need to be added to the first if condition:
if(type == Patents || type == Orkut || ... || type == MyDataset) {
...
}And in function general_load_data, the switch-case statements should be modified:
switch(type) {
case DataType::Patents : {
g->tri_cnt = Patents_tri_cnt;
}
...
...
case DataType::MyDataset : {
g->tri_cnt = Mydataset_tri_cnt;
}
}###Step3: Code changes in src/common.cpp
The function GetDataType should be changed.
Add a new if condition statement for MyDataset:
if( str == "MyDataset") {
type = DataType::MyDataset;
}After these steps, you can use MyDataset for pattern matching like others.